KR101498762B1 - Method and apparatus for monitoring insulation resistance - Google Patents

Abstract

There is provided an apparatus for monitoring an insulation resistance of a battery pack including a plurality of battery cells. The apparatus includes a slave unit for monitoring a resistance value of an internal insulation resistance for each of the plurality of battery cells, and a master unit for monitoring a resistance value of an external insulation resistance of the battery pack based on resistance values of the internal insulation resistance do.

Description

METHOD AND APPARATUS FOR MONITORING INSULATION RESISTANCE BACKGROUND OF THE INVENTION [0001]

The present invention relates to a secondary battery, and more particularly, to a method and apparatus for monitoring an insulation resistance of a secondary battery.

As the use of portable electric appliances such as video cameras, portable phones, and portable PCs is being activated, the importance of secondary batteries, which are mainly used as driving power sources, is increasing. In particular, the lithium secondary battery has a higher energy density per unit weight and can be rapidly charged as compared with conventional lead-acid batteries and other secondary batteries such as nickel-cadmium batteries, nickel-hydrogen batteries and nickel-zinc batteries. It is actively proceeding.

Unlike conventional primary batteries, which can not be charged, secondary batteries capable of charging and discharging are under active research in the development of advanced fields such as digital cameras, cellular phones, notebook computers, and hybrid vehicles. Examples of the secondary battery include a nickel-cadmium battery, a nickel-metal hydride battery, a nickel-hydrogen battery, and a lithium secondary battery. Among them, the lithium secondary battery has a higher operating voltage than the nickel-cadmium battery or the nickel-metal hydride battery, and has excellent energy density per unit weight.

A secondary battery used in an electric vehicle generally needs to provide a large capacity of 100A to 300A. If deterioration or damage of the secondary battery's battery occurs, the leakage current may increase the power loss or seriously affect the passenger. Therefore, it is important to keep the insulation of the secondary battery in a good state.

U.S. Published Patent Application No. 2011/0115490 discloses a method of measuring the insulation resistance value using the sum of the cathode voltage and the anode voltage of a battery.

A method of monitoring the resistance value of the insulation resistance of the secondary battery is needed.

The present invention provides an apparatus and method for monitoring insulation resistance of a battery pack including a plurality of battery cells.

In one aspect, an apparatus for monitoring an insulation resistance of a battery pack including a plurality of battery cells is provided. The apparatus includes a slave unit for monitoring a resistance value of an internal insulation resistance for each of the plurality of battery cells, and a master unit for monitoring a resistance value of an external insulation resistance of the battery pack based on resistance values of the internal insulation resistance do.

The external insulation resistance may include an insulation resistance to the positive electrode of the battery pack and an insulation resistance to the negative electrode of the battery pack.

The internal insulation resistance may include an insulation resistance to an anode of each of the plurality of battery cells.

The internal insulation resistance for each of the plurality of battery cells may be sequentially determined for each of the plurality of battery cells.

In another aspect, a method of monitoring an insulation resistance of a battery pack including a plurality of battery cells is provided. The method includes monitoring a resistance value of an internal insulation resistance for each of the plurality of battery cells and monitoring a resistance value of an external insulation resistance of the battery pack based on resistance values of the internal insulation resistance .

In another aspect, a secondary battery system includes a battery pack including a plurality of battery cells, and a monitoring device for monitoring an insulation resistance of the battery pack, the monitoring device including an internal insulation resistance And a master unit for monitoring a resistance value of the external insulation resistance of the battery pack based on the resistance values of the internal insulation resistance.

The resistance value of the insulation resistance can be detected for a battery pack including a plurality of battery cells. The leakage current of the secondary battery can be measured.

1 is a block diagram showing an electric vehicle according to an embodiment of the present invention.
2 is a block diagram illustrating an insulation resistance monitoring apparatus according to an embodiment of the present invention.
3 shows an equivalent circuit for estimating the insulation resistance of one battery cell.
Figure 4 shows an equivalent circuit of the _{ADC _} V _TOP.
5 shows an equivalent circuit for the V _{_ ADC Bottom.}
6 is a timing diagram illustrating a method of measuring insulation resistance according to an embodiment of the present invention.

An electric vehicle refers to a vehicle that includes one or more electric motors as propulsive forces. The energy used to propel the electric vehicle includes an electrical source such as a rechargeable battery and / or a fuel cell. The electric vehicle may be a hybrid electric vehicle that uses a combustion engine as another power source.

1 is a block diagram showing an electric vehicle according to an embodiment of the present invention.

The electric vehicle 10 includes a battery pack 11, a controller 12, a motor 13, and an insulation resistance monitoring device 100.

The battery pack 11 is an electric storage source used for driving the electric vehicle 10. The battery pack 11 provides a driving force to the motor 13 as a load and can be charged by a generator (not shown) in accordance with driving of the motor 13 and / or an internal combustion engine (not shown). The capacity of the battery pack 11 may be 100A to 300A.

The battery pack 11 includes a plurality of secondary battery cells and a battery management module for monitoring the state of charge of each battery cell.

The controller 12 is an electronic control device for controlling the state of the electric vehicle 10.

The insulation resistance monitoring apparatus 100 monitors the resistance value of the insulation resistance of the battery pack 11 according to the embodiments of the present invention. The insulation resistance monitoring device 100 may be part of the battery management module of the battery pack 11 or may be part of the controller 12. [ The insulation resistance monitoring device 100 may be an independent device.

Controller 12 and insulation resistance monitoring device 100 may comprise a processor, an application-specific integrated circuit (ASIC), other chipset, logic circuitry and / or a data processing device. When the embodiment is implemented in software, the above-described techniques may be implemented with modules (processes, functions, and so on) that perform the functions described above. The module is stored in memory and can be executed by the processor. The memory may be internal or external to the processor and may be coupled to the processor by any of a variety of well known means.

A method of measuring insulation resistance according to an embodiment of the present invention will now be described.

First, we define the terms as follows.

R _{Leak (+)} : Insulation resistance between positive electrode and ground of battery pack

R _{Leak (-)} : Insulation resistance between negative _{pole of} battery pack and ground

R _{Leak ( Bus Bar n)} : Insulation resistance between the positive electrode of the nth battery cell and ground

_{R Isol _ Sn, R Ref _} Sn: R Leak (Bus _{Bar n)} to measure R _{Leak ( Bus Bar n)}

_Isol R, R _{Ref: Leak} R ₍₊₎ and R _{Leak - (-) Leak} R ₍₊₎ and R _Leak to measure ₍₎ resistors connected in series with each

Switch_Sn: n anode and R _{Isol _} switch between _Sn, R _{Ref _ Sn} of the second battery cell

Switch_M1: Switch between the anode of the battery pack and R _Isol , R _Ref

Switch_M2: Switch between the cathode of the battery pack and R _Isol , R _Ref

V _{_ ADC Bus n:} when Switch_Sn is ON, R _{_ Isol} voltage measured between _Sn and _Sn R _{Ref _}

V _{ADC _ TOP:} When Switch_M1 is ON, the voltage measured between R _Isol, R _Ref

V _{ADC _ Bottom:} When Switch_M2 is ON, the voltage measured between R _Isol, R _Ref

_{V Pack _ Top: R Leak (} Bus _{Bar n)} between the anode of the module with the smallest value and the positive electrode of the battery pack

_{V Pack _ Bottom: R Leak (} Bus _{Bar n)} between the anode of the smallest module and the battery pack cathode

V _Pack : Battery Pack Voltage

2 is a block diagram illustrating an insulation resistance monitoring apparatus according to an embodiment of the present invention.

The insulation resistance monitoring apparatus 100 includes a slave unit 110 and a master unit 120.

The slave unit 110 has an internal insulation resistance R _{Leak ( Bus Bar n)} . Here, it is assumed that there are ten battery cells, but the number of battery cells is not limited. Each internal insulation Switch_Sn corresponding to the resistance is sequentially turned on, and R _{Leak ( Bus Bar 1)} , R _{Leak (Bus Bar 2)} , ..., R _{Leak ( Bus Bar 11)} . The smallest value of internal insulation resistance is called R _{Leak (Bus Bar )} .

The master unit 120 receives the R _{Leak ( Bus Bar )} , the insulation resistances R _{Leak (+)} and R _{Leak (-)} of the battery pack 11 are monitored. The master unit 120 includes a first measurement unit 122 and a second measurement unit 124. The insulation resistances R _{Leak (+)} and R _{Leak (-)} are measured through the first measurement unit 122 and the second measurement unit 124. The first measuring unit 122 measures the insulation resistance R _{Leak (+)} at the positive electrode of the battery pack 11. The second measuring unit 124 measures the insulation resistance R _{Leak (-)} of the negative electrode of the battery pack 11. R _{Leak (+)} and R _{Leak (-)} are also referred to as external insulation resistance in that they are insulation resistance for each terminal of the battery pack (11).

Now, a method of estimating the insulation resistance in a circuit constructed as shown in Fig. 2 will be described.

3 shows an equivalent circuit for estimating the insulation resistance of one battery cell.

When Switch_S1 is ON, R _{Leak ( Bus Bar1 )} can be determined as follows

R _{Leak ( Bus Bar1 )} , then Switch_S2 to Switch_S11 are sequentially turned on to set R _{Leak (Bus Bar2 )} to R _{Leak ( Bus Bar11 )} can be obtained.

Figure 4 shows an equivalent circuit of the _{ADC _} V _TOP.

From the equivalent circuit V _{TOP _ ADC} may be modeled by the following equation.

5 shows an equivalent circuit for the V _{_ ADC Bottom.}

From the equivalent circuit V _{Bottom _ ADC} may be modeled by the following equation.

The following parameters are defined to obtain the insulation resistances R _{Leak (+)} and R _{Leak (-)} .

Using the above parameters and Equations 1, 2 and 3, the following can be expressed.

As a result, the insulation resistances R _{Leak (+)} and R _{Leak (-)} can be expressed by the following equations.

6 is a timing diagram illustrating a method of measuring insulation resistance according to an embodiment of the present invention.

It is divided into two steps to measure insulation resistance. The first is the internal insulation resistance measurement step (① ~ ④), and the second is the external insulation resistance measurement step (⑤⑥).

In step 1, turn on Switch_S1 and set R _{Leak ( Bus Bar 1)} is obtained. In step (2), switch_S2 is turned on to set R _{Leak ( Bus Bar 2)} is obtained. In this way, the switch Switch_Sn is sequentially turned on to obtain the internal insulation resistance. In step ④, turn on Switch_S11 to obtain R _{Leak (Bus Bar 11)} . After obtaining all the internal insulation resistance, R _{Leak ( Bus Bar )} can be determined.

ON ⑤ to the Switch_M1 step, measure the V _{ADC _ TOP.} ⑥ to the ON Switch_M2 in step measures the V _{_ ADC Bottom.}

Using Equation (7 ₎ , the insulation resistances R _{Leak (+)} and R _{Leak (-)} can be obtained.

Claims (12)

An apparatus for monitoring an insulation resistance of a battery pack including a plurality of battery cells,
A slave unit for monitoring a resistance value of an internal insulation resistance for each of the plurality of battery cells; And
A negative electrode voltage between the positive electrode and the ground of the battery pack and a negative electrode voltage between the negative electrode and the ground of the battery pack are measured and the smallest resistance value among the resistance values of the positive electrode voltage, And a master unit for calculating a resistance value of the external insulation resistance of the battery pack and monitoring a resistance value of the external insulation resistance of the battery pack. The method according to claim 1,
Wherein the external insulation resistance includes an insulation resistance to a positive electrode of the battery pack and an insulation resistance to a negative electrode of the battery pack. The method according to claim 1,
Wherein the internal insulation resistance includes an insulation resistance to an anode of each of the plurality of battery cells. The method of claim 3,
Wherein an internal insulation resistance for each of the plurality of battery cells is sequentially determined for each of the plurality of battery cells. delete A method for monitoring an insulation resistance of a battery pack including a plurality of battery cells,
Monitoring a resistance value of an internal insulation resistance for each of the plurality of battery cells;
Measuring an anode voltage between an anode and a ground of the battery pack;
Measuring a cathode voltage between a cathode and a ground of the battery pack; And
Calculating a resistance value of the external insulation resistance of the battery pack using the resistance value of the anode voltage, the cathode voltage, and the resistance value of the internal insulation resistance, The method comprising the steps of: The method according to claim 6,
Wherein the external insulation resistance includes an insulation resistance to a positive electrode of the battery pack and an insulation resistance to a negative electrode of the battery pack. The method according to claim 6,
Wherein the internal insulation resistance includes an insulation resistance to an anode of each of the plurality of battery cells. 9. The method of claim 8,
Wherein the internal insulation resistance for each of the plurality of battery cells is sequentially determined for each of the plurality of battery cells. delete A battery pack including a plurality of battery cells; And
And a monitoring device for monitoring the insulation resistance of the battery pack,
The monitoring device
A slave unit for monitoring a resistance value of an internal insulation resistance for each of the plurality of battery cells; And
A negative electrode voltage between the positive electrode and the ground of the battery pack and a negative electrode voltage between the negative electrode and the ground of the battery pack are measured and the smallest resistance value among the resistance values of the positive electrode voltage, And a master unit for calculating a resistance value of the external insulation resistance of the battery pack and monitoring a resistance value of the external insulation resistance of the battery pack. 12. The method of claim 11,
Wherein an internal insulation resistance for each of the plurality of battery cells is determined sequentially for each of the plurality of battery cells.

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